Avaliação de inibidor de corrosão indicado para sistemas de aço carbono submetidos a meios com CO2 e H2S.

Abstract

Corrosion is a serious problem that affects the operational routines of the oil exploration industry. The formation water has chlorides, carbon dioxide and sulfuric gas, which after dissolved form acids that affect the integrity of pipes and equipment. This work aims to study the behavior of a corrosion inhibitor based on amine and imidazoline under different conditions. Solutions of 0.2% NaCl, 3.5% NaCl and 8% NaCl were used, as well as application of corrosion inhibitor at concentrations of 50 ppm and 100 ppm (parts per million). The influence of two gases, CO2 (Carbon Dioxide) and H2S (Sulfuric Acid) dissolved, acting separately or simultaneously in the medium, was analyzed. In order to evaluate the inhibitors, the following tests were performed: Open Circuit Potential (OCP) of each system and subsequent analysis of Linear Potentiodynamic Polarization and Electrochemical Impedance Spectrometry. In addition, Gravimetrical Techniques (Mass Loss) tests were also used to compare the results of the Electrochemical Tests. The surfaces of the samples were characterized by optical microscopy. For all environment studied, the application of the corrosion inhibitor increased the corrosion resistance of the systems, and in general, it was more efficient at concentrations of 100 ppm. For the medium with 3.5% NaCl and CO2 solution, the concentration of 50 ppm showed better results.